According to USA Today, Mueller said the FBI has "very few" drones and uses them in "a very minimal way and very seldom." But he didn't give numbers, so we don't know whether "very few" means a handful or "a number dwarfed by the Central Intelligence Agency's stockpile." Ditto for the meanings of "minimal way" and "very seldom."

He also said that the agency is drawing up guidelines for the use of drones, which suggests it's been making up the rules for their use as it goes along.

[Updated, 2:29 p.m. June 19: Mueller's remark about guidelines also raised eyebrows on Capitol Hill. Said Sen. Mark Udall (D-Colo.), "Unmanned aerial systems have the potential to more efficiently and effectively perform law enforcement duties, but the American people expect the FBI and other government agencies to first and foremost protect their constitutional rights. I am concerned the FBI is deploying drone technology while only being in the 'initial stages' of developing guidelines to protect Americans' privacy rights. I look forward to learning more about this program and will do everything in my power to hold the FBI accountable and ensure its actions respect the U.S. Constitution."]

Having said all that, I have to admit that I'm not troubled by Mueller's revelation. Maybe it just pales in comparison to the recent revelations about the National Security Agency's monitoring of phones and the Internet. Or maybe I'm just in the tank for the FBI.

The real issue to me is the circumstances under which the FBI -- or any law enforcement agency -- uses drones. The type of surveillance investigators conduct depends on how strong a case they've been able to assemble against a suspect; the weaker the case, the less intrusive and persistent the surveillance can be. Drones are more intrusive than an agent tailing a suspect in a car, because drones can see into places that aren't public, such as backyards. But they arguably aren't as intrusive as wiretaps -- at least not until the technology improves for eavesdropping from a distance.

But what do you think? Take our inconclusive poll, leave a comment or do both!